Method for producing powdered cellulose

Abstract

The present invention relates to a method for producing powdered cellulose. The method comprises the steps of providing dry pulp starting material, heat treating the dry pulp starting material to a temperature of 100-200° C., for less than 1 hour, and refining the heat-treated dry pulp starting material to particles having d97<500 μm.

1 . A method for producing powdered cellulose, wherein the method comprises the steps of:
 a) providing dry pulp starting material;   b) heat treating the dry pulp starting material to a temperature of 100-250° C., for less than 1 hour; and   c) refining the heat-treated dry pulp starting material to particles having d97<500 μm.   
     
     
         2 . A method for producing powdered cellulose according to  claim 1 , wherein the heat treatment of step b) is performed for at least 5 minutes, at least 10 minutes, or at least 15 minutes. 
     
     
         3 . A method for producing powdered cellulose according to  claim 1 , wherein the refining of step c) is performed at a pressure below atmospheric pressure. 
     
     
         4 . A method for producing powdered cellulose according to  claim 1 , wherein step b) is performed to a post color (PC)-number below 5, preferably below 1, the PC-number being defined by the formulas:
   PC-number=100×[( k/s ) t −( k/s ) t=0 ]
   k/s=(1−R ∞ ) 2 /(2R ∞ ) wherein R ∞  is the measured diffuse reflectance at 457 nm.   
     
     
         5 . A method for producing powdered cellulose according to  claim 1 , wherein the refining of step c) is performed in at least one of a hammer mill, a ball mill, a stone mill, an impact mill, and a knife mill. 
     
     
         6 . A method for producing powdered cellulose according to  claim 1 , wherein the refining of step c) is performed in at least two refining steps, comprising a first refining to a particle size of d97<2000 μm, and a second refining to a particle size of d97<400 μm. 
     
     
         7 . A method for producing powdered cellulose according to  claim 6 , wherein the first refining is performed in a hammer mill, an impact mill, a knife mill or air jet mill, and the second refining is performed in a ball mill, a stone mill, an impact mill, or a knife mill. 
     
     
         8 . A method for producing powdered cellulose according to  claim 1 , wherein the dry pulp starting material comprises softwood Kraft paper pulp, hardwood Kraft paper pulp, hardwood sulphite pulp, softwood sulphite pulp, mechanical pulp (MP), softwood dissolving pulp, hardwood dissolving pulp, or mixtures thereof. 
     
     
         9 . A method for producing powdered cellulose according to  claim 1 , wherein the dry pulp starting material comprises flash-dried pulp. 
     
     
         10 . A method for producing powdered cellulose according to  claim 1 , wherein the dry pulp starting material comprises dissolving pulp. 
     
     
         11 . A method for producing powdered cellulose according to  claim 1 , wherein refining of step c) is performed to a particle size of d97<300 μm, preferably to a particle size of d97<200 μm, more preferably to a particle size of d97<100 μm. 
     
     
         12 . A method for producing powdered cellulose according to  claim 1 , further comprising a step of heat preservation of the heat-treated dry pulp starting material until the refining of step c). 
     
     
         13 . A product obtained by the process according to  claim 1 , wherein said product has a microbe content below 14 000 cfu/g, 12 000 cfu/g, 000 cfu/g, 5 000 cfu/g, 2 000 cfu/g, or 1 000 cfu/g. 
     
     
         14 . (canceled) 
     
     
         15 . A product according to  claim 13 , wherein the dry pulp starting material comprises dissolving pulp. 
     
     
         16 . A product according to  claim 13 , wherein the dry pulp starting material comprises flash-dried pulp. 
     
     
         17 . Use of the product according to  claim 13 , to increase the fiber content within a food product, within a feed product or within a pharmaceutic product.